Thursday, 19 September 2013

The Amplituhedron

This is an article which gives one the pleasant but illusory sense of being just on the verge of understanding something quite important. It starts "Physicists have discovered a jewel-like geometric object that dramatically simplifies calculations of particle interactions and challenges the notion that space and time are fundamental components of reality" and carries on from there.Here are some bits I liked:

"The positive Grassmannian is the slightly more grown-up cousin of the inside of a triangle." I liked '"slightly" and the idea that there might be family gatherings where positive Grassmanians just manage to pull rank on the insides of triangles.

"They have also found a “master amplituhedron” with an infinite number of facets, analogous to a circle in 2-D, which has an infinite number of sides. Its volume represents, in theory, the total amplitude of all physical processes. Lower-dimensional amplituhedra, which correspond to interactions between finite numbers of particles, live on the faces of this master structure." One can just imagine the stunted minor amplitudehra clinging on to the surfaces of their majestic master for dear life.

"The discovery of the amplituhedron could cause an even more profound shift, Arkani-Hamed said. That is, giving up space and time as fundamental constituents of nature and figuring out how the Big Bang and cosmological evolution of the universe arose out of pure geometry.

"“In a sense, we would see that change arises from the structure of the object,” he said. “But it’s not from the object changing. The object is basically timeless.”" To the layman, this all sounds very much like theology, except that Mr Arkani-Hamed would have said "in a very real sense" instead.

About Further or Alternatively (FOA)

FOA read PPE at Oxford and is now a barrister based in London.
"Further or alternatively" is a phrase used by barristers to introduce a new argument that may or may not be consistent with the previous ones: FOA may or may not be consistent with your other reading.